1. Field of the Invention
The present invention relates to a harness protecting structure which is optimally adapted for use with a telescopic steering column capable of adjusting steering wheel elevation to obtain an optimal driving position.
2. Description of the Prior Disclosure
Recently, there have been proposed and developed various protecting structures for a harness arranged along a telescopic steering column, such harnesses generally comprise a plurality of lead wires, such as horn and switch wires, wires employed for an air-bag system and the like. As is generally known, such harness protecting structures are designed in such a manner as to assure protection of the harness, and to absorb expansion/contraction of the harness occurring according to telescopic motion of the steering column, and in addition to organize complicated wiring along the steering column.
One such conventional protecting structure for a harness arranged on the outer periphery of a telescopic steering column has been disclosed in Japanese Utility Model Second Publication (Jikko Showa) NO. 63-32527. Such a conventional harness protecting structure for a telescopic steering column includes a harness housing provided beneath a combination switch assembly attached to the steering column, for operably accommodating an intermediate helically arranged steering harness section in a manner so as to increase or decrease a diameter of the helical harness section in accordance with telescopic motion of the steering column. The harness housing includes a partition wall for defining a helical passageway for the helical harness section, in combination with the inner wall of the housing. The partition wall is also provided to regulatingly guide the helical harness section in the harness housing. In the conventional harness protecting structure as previously described, since at least one turned intermediate helical harness section having a relatively large diameter (and consequently a relatively large rigidity) is helically accommodated in the harness housing through the partition wall, the outer peripheral surface of the helical harness section contacts the inner peripheral surface of the harness housing and the partition wall with a relatively large contact surface. Under such a helically accommodated state of the intermediate steering harness section, a relatively large torsional stress continuously occurs at the harness section and abrasion occurs at the contact surface during telescopic motion of the steering column. In addition, flexibility of the helical harness section is lowered due to its relatively high rigidity. Therefore, the life of the helical harness section may be reduced.
Furthermore, the conventional steering harness protecting structure provides a relatively great thickness towards the knees of the driver due to its helical structure. That is, a relatively great thickness of protecting structure is required for helically accommodating the harness section. As a result, knee space of the driver is reduced.